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International audienc
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Seabirds rarely cross major terrestrial barriers during seasonal migration, possibly because they have a limited ability to build up fat stores. For the first time, we tracked two Ivory Gulls with GPS loggers during spring migration from... more
Seabirds rarely cross major terrestrial barriers during seasonal migration, possibly because they have a limited ability to build up fat stores. For the first time, we tracked two Ivory Gulls with GPS loggers during spring migration from the wintering area in Davis Strait to the breeding colony in north‐east Greenland. While one bird migrated in March around the southern tip of Greenland, the other delayed migration until May and crossed the Greenland icecap north of 70°N, covering 1345 km in 29 h. Several aspects of the crossing were noteworthy: the track was remarkably direct, the bird made several stops (totalling 6 h) on the icecap, and the bird increased its flying altitude to nearly 3000 m over West Greenland and > 4000 m over East Greenland.
Research Interests: Information Systems, Zoology, Geography, Ecology, Ibis, and 3 moreArctic, Seabird, and Charadriiformes
Corpus "AGORA"Dans une définition étroite, la biodiversité ne transcrit qu’une des notions liées au fonctionnement de la Nature (organisation, complexité, spontanéité, continuités et diversité). Aujourd’hui, nombreux sont ceux... more
Corpus "AGORA"Dans une définition étroite, la biodiversité ne transcrit qu’une des notions liées au fonctionnement de la Nature (organisation, complexité, spontanéité, continuités et diversité). Aujourd’hui, nombreux sont ceux qui expriment le besoin de gérer les forêts (ou les composantes forestières d'espaces naturels) suivant un principe impératif de naturalité et recherchent une vision intégrative et partagée sur tout ce que cela sous-entend. Les idées reçues sont nombreuses sur ce concept scientifique novateur et ses applications. Le colloque Biodiversité, Naturalité, Humanité - Pour inspirer la gestion des forêts a été organisé par le WWF France, Réserves Naturelles de France (RNF), le Réseau Ecologique Forestier Rhônes-Alpes (REFORA), le comité Man and Biosphere France (MAB France) et le Cemagref à Chambéry (Savoie, France) du 27 au 31 octobre 2008. Son objectif principal était de contribuer à appréhender la naturalité en tant que paramètre intégrateur pour l'évaluation du fonctionnement des écosystèmes forestiers, la qualification des pratiques de gestion qui y sont développées et la définition des relations entre les sociétés humaines et ces derniers
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National audienceLe but de cette étude est d’évaluer l’influence respective de l’exploitation forestière, de la structure et du paysage sur les communautés de chiroptères et d’oiseaux en forêt exploitée et non exploitée en France. Nos... more
National audienceLe but de cette étude est d’évaluer l’influence respective de l’exploitation forestière, de la structure et du paysage sur les communautés de chiroptères et d’oiseaux en forêt exploitée et non exploitée en France. Nos résultats montrent que la richesse totale de l'avifaune et des chiroptères, la richesse des oiseaux forestiers et des chiroptères de lisière augmente faiblement avec le volume total de bois mort. La richesse des oiseaux généralistes, des omnivores et des cavicoles est légèrement plus élevée dans les forêts non exploitées. Les chiroptères glaneurs sont positivement influencés par la densité de bois mort debout. Par contre, les variables paysagères retenues n’ont que peu d’influence sur la biodiversité. Malgré des effets assez faibles, notre étude confirme l’intérêt du bois mort pour la diversité de ces groupes
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ABSTRACTCamera trap arrays can generate thousands to millions of images that require exorbitant time and effort to classify and annotate by trained observers. Computer vision has evolved as an automated alternative to manual... more
ABSTRACTCamera trap arrays can generate thousands to millions of images that require exorbitant time and effort to classify and annotate by trained observers. Computer vision has evolved as an automated alternative to manual classification. The most popular computer vision solution is the supervised Machine Learning technique, which uses labeled images to train automated classification algorithms.We propose a multi-step semi-automated workflow that consists of (1) identifying and separating bad-from good-quality images, (2) parsing good images into animals, humans, vehicles, and empty, and (3) cropping animals from images and classifying them into species for manual inspection. We trained, validated, and evaluated this approach using 548,627 images from 46 cameras in two regions of the Arctic (northeastern Norway, and Yamal Peninsula, Russia).We obtained an accuracy of 0.959 for all three steps combined with the complete year test data set at Varanger and 0.922 at Yamal, reducing the number of images that required manual inspection to 7.9% of the original set from Varanger and 3.2% from Yamal.Researchers can modify this multi-step process to meet their specific needs for monitoring and surveying wildlife, providing greater flexibility than current options available for image classification.
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International audienceIn Western Europe, the long history of forest management over the past centuries has shaped both landscape and local scale forest structure, presumably altering the biodiversity of forest dwelling species. In France,... more
International audienceIn Western Europe, the long history of forest management over the past centuries has shaped both landscape and local scale forest structure, presumably altering the biodiversity of forest dwelling species. In France, the strict forest reserves network has been created to serve as a witness to gauge the effects of management on forest structures and dynamics: it currently covers 0.3% of national territory, distributed over 200 sites representative of the main forest types. However, to date, research comparing biodiversity in managed and unmanaged forests remains strikingly poor in Western Europe, and hardly proposes a broad taxonomic assessment. In order to fill the gap in knowledge in the French context, we studied forest structure and biodiversity in lowland oak-beech-hornbeam forests, and in montane beech-fir-spruce forests. We compared living and dead wood amounts and biodiversity of 6 taxa (vascular plants, saproxylic fungi, birds, bats, carabids and saproxylic beetles) 15 strict forest reserves where forest management has been abandoned for at least 20 years and adjacent managed forests, totalizing 213 plots. Relatively to managed forest, stands in unmanaged forest host larger amounts of old-growth components (deadwood volumes, number of large trees) as well as higher basal areas, whereas other stand characteristics did not differ significantly. Saproxylic fungi responded significantly to management abandonment, their total richness increasing with time since last harvesting. Responses of the other taxonomic groups were less clear and further analyses correlating forest structure with taxa or ecological groups are necessary to better understand the mechanisms associating biodiversity and forest management. The applied outcome of this multitaxonomic approach is to validate indirect biodiversity indicators on a broad gradient of forest management. This project constitutes the first reference for mixed beech forests in France and may help managers to define thresholds in terms of biodiversity oriented measures
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Research Interests: Biology, Ecology, Biological Sciences, Tooth wear, Arctic, and 4 moreArctic Fox, Polar Biology, Vulpes, and lagopus
National and international forest biodiversity assessments largely rely on indirect indicators, based on elements of forest structure that are used as surrogates for species diversity. These proxies are reputedly easier and cheaper to... more
National and international forest biodiversity assessments largely rely on indirect indicators, based on elements of forest structure that are used as surrogates for species diversity. These proxies are reputedly easier and cheaper to assess than biodiversity. Tree microhabitats—tree‐borne singularities such as cavities, conks of fungi or bark characteristics—have gained attention as potential forest biodiversity indicators. However, as with most biodiversity indicators, there is a lack of scientific evidence documenting their quantitative link with the biodiversity they are supposed to assess. We explored the link between microhabitat indices and the richness and abundance of three taxonomic groups: bats, birds and saproxylic beetles. Using a nation‐wide multi‐taxon sampling design in France, we compared 213 plots located inside and outside strict forest reserves. We hypothesized that the positive effect setting aside forest reserves has on biodiversity conservation is indirectly d...
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Le projet Gestion forestiere, Naturalite et Biodiversite a pour but d'etudier le lien entre biodiversite, exploitation forestiere et naturalite en comparant des parcelles exploitees a des parcelles non-exploitees (Reserves Biologiques... more
Le projet Gestion forestiere, Naturalite et Biodiversite a pour but d'etudier le lien entre biodiversite, exploitation forestiere et naturalite en comparant des parcelles exploitees a des parcelles non-exploitees (Reserves Biologiques Integrales ou parties integrales de Reserves Naturelles). En partenariat avec l'ONF, RNF et l'INRA, nous travaillons depuis 2008 sur des reserves integrales soustraites a l'exploitation depuis au moins 20 ans. L'etude repose sur l'echantillonnage de 7 groupes taxonomiques : plantes vasculaires, mousses, champignons, chauve-souris, oiseaux, coleopteres carabiques et saproxyliques.
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The ongoing decline of sea ice threatens many Arctic taxa, including the ivory gull. Understanding how ice-edges and ice concentrations influence the distribution of the endangered ivory gulls is a prerequisite to the implementation of... more
The ongoing decline of sea ice threatens many Arctic taxa, including the ivory gull. Understanding how ice-edges and ice concentrations influence the distribution of the endangered ivory gulls is a prerequisite to the implementation of adequate conservation strategies. From 2007 to 2013, we used satellite transmitters to monitor the movements of 104 ivory gulls originating from Canada, Greenland, Svalbard-Norway and Russia. Although half of the positions were within 41 km of the ice-edge (75% within 100 km), approximately 80% were on relatively highly concentrated sea ice. Ivory gulls used more concentrated sea ice in summer, when close to their high-Arctic breeding ground, than in winter. The best model to explain the distance of the birds from the ice-edge included the ice concentration within approximately 10 km, the month and the distance to the colony. Given the strong links between ivory gull, ice-edge and ice concentration, its conservation status is unlikely to improve in the current context of sea-ice decline which, in turn, will allow anthropogenic activities to develop in regions that are particularly important for the species.
Research Interests: Biology, Ecology, Endangered Species, Medicine, Arctic, and 3 moreHabitat, Satellite Tracking, and Seabird
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Migratory birds generally have tightly scheduled annual cycles, in which delays can have carry-over effects on the timing of later events, ultimately impacting reproductive output. We tested whether migration schedules among eight... more
Migratory birds generally have tightly scheduled annual cycles, in which delays can have carry-over effects on the timing of later events, ultimately impacting reproductive output. We tested whether migration schedules among eight breeding populations of Arctic SkuasStercorarius parasiticusbetween Greenland and Siberia differ as a function of their use of seven widely divergent wintering areas across the Atlantic Ocean, Mediterranean Sea and Indian Ocean, and predicted that migrations over larger distances, with tighter schedules, would provide less room for compensating delays. Breeding at higher latitudes led not only to later reproduction and migration, but also faster spring migration and shorter time between return to the breeding area and clutch initiation. Wintering area was consistent within individuals among years; and more distant areas were associated with more time spent on migration and less time in the wintering areas. Skuas adjusted the period spent in the non-breedin...
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Background Herbivores modify the structure and function of tundra ecosystems. Understanding their impacts is necessary to assess the responses of these ecosystems to ongoing environmental changes. However, the effects of herbivores on... more
Background Herbivores modify the structure and function of tundra ecosystems. Understanding their impacts is necessary to assess the responses of these ecosystems to ongoing environmental changes. However, the effects of herbivores on plants and ecosystem structure and function vary across the Arctic. Strong spatial variation in herbivore effects implies that the results of individual studies on herbivory depend on local conditions, i.e., their ecological context. An important first step in assessing whether generalizable conclusions can be produced is to identify the existing studies and assess how well they cover the underlying environmental conditions across the Arctic. This systematic map aims to identify the ecological contexts in which herbivore impacts on vegetation have been studied in the Arctic. Specifically, the primary question of the systematic map was: “What evidence exists on the effects of herbivores on Arctic vegetation?”. Methods We used a published systematic map ...
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Kubelka et al . (Reports, 9 November 2018, p. 680) claim that climate change has disrupted patterns of nest predation in shorebirds. They report that predation rates have increased since the 1950s, especially in the Arctic. We describe... more
Kubelka et al . (Reports, 9 November 2018, p. 680) claim that climate change has disrupted patterns of nest predation in shorebirds. They report that predation rates have increased since the 1950s, especially in the Arctic. We describe methodological problems with their analyses and argue that there is no solid statistical support for their claims.
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Research Interests: Zoology, Geography, Conservation, Behavior, Ecology, and 11 moreSeabirds, Navigation, Models, Tracking, Flexibility, Wildlife, Dispersal, Atlantic, Ocean, Repeatability, and Seabird
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Most birds incubate their eggs to allow embryo development. This behaviour limits the ability of adults to perform other activities. Hence, incubating adults trade-off incubation and nest protection with foraging to meet their own needs.... more
Most birds incubate their eggs to allow embryo development. This behaviour limits the ability of adults to perform other activities. Hence, incubating adults trade-off incubation and nest protection with foraging to meet their own needs. Parents can either cooperate to sustain this trade-off or incubate alone. The main cause of reproductive failure at this reproductive stage is predation and adults reduce this risk by keeping the nest location secret. Arctic sandpipers are interesting biological models to investigate parental care evolution as they may use several parental care strategies. The three main incubation strategies include both parents sharing incubation duties ("biparental"), one parent incubating alone ("uniparental"), or a flexible strategy with both uniparental and biparental incubation within a population ("mixed"). By monitoring the incubation behaviour in 714 nests of seven sandpiper species across 12 arctic sites, we studied the relationship between incubation strategy and nest predation. First, we described how the frequency of incubation recesses (NR), their mean duration (MDR), and the daily total duration of recesses (TDR) vary among strategies. Then, we examined how the relationship between the daily predation rate and these components of incubation behaviour varies across strategies using two complementary survival analysis. For uniparental and biparental species, the daily predation rate increased with the daily total duration of recesses and with the mean duration of recesses. In contrast, daily predation rate increased with the daily number of recesses for biparental species only. These patterns may be attributed to two independent mechanisms: cryptic incubating adults are more difficult to locate than unattended nests and adults departing the nest or feeding close to the nest can draw predators' attention. Our results demonstrate that incubation behaviour as mediated by incubation strategy has important consequences for sandpipers' reproductive success.
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National audienc
National audienceD'envergure nationale, l'objectif principal du projet "gestion forestière, naturalité et biodiversité (GNB)" est d'étudier l'impact de l'arrêt de l'exploitation forestière sur la... more
National audienceD'envergure nationale, l'objectif principal du projet "gestion forestière, naturalité et biodiversité (GNB)" est d'étudier l'impact de l'arrêt de l'exploitation forestière sur la structure des peuplements et sur la biodiversité
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<p>(a) Long-tailed Skua, (b) Arctic Tern and (c) Sabine's Gull. Contours are graphically inferred from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0064614#pone-0064614-g001"... more
<p>(a) Long-tailed Skua, (b) Arctic Tern and (c) Sabine's Gull. Contours are graphically inferred from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0064614#pone-0064614-g001" target="_blank">Figure 1</a> (panels 1–8), Egevang et al <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0064614#pone.0064614-Egevang1" target="_blank">[29]</a> and Stenhouse et al <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0064614#pone.0064614-Stenhouse1" target="_blank">[25]</a>, respectively. Blue: autumn flyways; Red: wintering grounds; Yellow: spring flyways.</p
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La gestion durable des forets repose largement sur la biodiversite dont le fonctionnement reste cependant encore tres insuffisamment connu. Il en decoule la necessite d’ameliorer, de maniere generale, le socle de connaissances relatif a... more
La gestion durable des forets repose largement sur la biodiversite dont le fonctionnement reste cependant encore tres insuffisamment connu. Il en decoule la necessite d’ameliorer, de maniere generale, le socle de connaissances relatif a la biodiversite et, plus particulierement, d’analyser les interactions entre changement climatique, productivite forestiere et biodiversite en foret. Par ailleurs, les strategies et decisions des acteurs influent sur ces interactions et constituent egalement des objets d’etude a privilegier. C’est pourquoi le programme de recherche « Biodiversite, gestion forestiere et politiques publiques » a lance en 2013 un appel a projets de recherche avec deux entrees : - l’une par les sciences de la nature axee sur le changement climatique, les mesures de gestion et la dynamique de la biodiversite dans les ecosystemes ; - l’autre par les sciences humaines et sociales sur les strategies et decisions des acteurs, la gouvernance et les politiques publiques corresp...